[PATCH] [RISCV] Add RTEMS support

[Palmer Dabbelt]

It appears to work for me: I can generate a simple no-op executable and link it
with multilib.  I don't know anything about RTEMS, so I'm just going to trust
it'll actually work :).  We're not going to have bandwidth to test this, but if
you're interested there's some support for running the GCC test suite in our
super-repo

  https://github.com/riscv/riscv-gnu-toolchain

I committed the patch as

  https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=250632

Thanks a bunch!

On Thu, 27 Jul 2017 07:12:42 PDT (-0700), kito.cheng@gmail.com wrote:
> Hi Sebastian:
> LGTM, I've test riscv32-rtems-gcc is buildable.
>
> Thanks for you patch :)
>
> Hi Palmer:
> Could you help to commit this patch ?
>
> Thanks.
>
> On Thu, Jul 27, 2017 at 7:05 PM, Sebastian Huber
> <sebastian.huber@embedded-brains.de> wrote:
>> gcc/
>>         * config.gcc (riscv*-*-elf*): Add (riscv*-*-rtems*).
>>         * config/riscv/rtems.h: New file.
>> ---
>>  gcc/config.gcc           |  7 ++++++-
>>  gcc/config/riscv/rtems.h | 31 +++++++++++++++++++++++++++++++
>>  2 files changed, 37 insertions(+), 1 deletion(-)
>>  create mode 100644 gcc/config/riscv/rtems.h
>>
>> diff --git a/gcc/config.gcc b/gcc/config.gcc
>> index aab7f65c1df..f28164646c3 100644
>> --- a/gcc/config.gcc
>> +++ b/gcc/config.gcc
>> @@ -2040,7 +2040,7 @@ riscv*-*-linux*)
>>         # automatically detect that GAS supports it, yet we require it.
>>         gcc_cv_initfini_array=yes
>>         ;;
>> -riscv*-*-elf*)
>> +riscv*-*-elf* | riscv*-*-rtems*)
>>         tm_file="elfos.h newlib-stdint.h ${tm_file} riscv/elf.h"
>>         case "x${enable_multilib}" in
>>         xno) ;;
>> @@ -2053,6 +2053,11 @@ riscv*-*-elf*)
>>         # Force .init_array support.  The configure script cannot always
>>         # automatically detect that GAS supports it, yet we require it.
>>         gcc_cv_initfini_array=yes
>> +       case ${target} in
>> +       riscv*-*-rtems*)
>> +         tm_file="${tm_file} rtems.h riscv/rtems.h"
>> +         ;;
>> +       esac
>>         ;;
>>  mips*-*-netbsd*)                       # NetBSD/mips, either endian.
>>         target_cpu_default="MASK_ABICALLS"
>> diff --git a/gcc/config/riscv/rtems.h b/gcc/config/riscv/rtems.h
>> new file mode 100644
>> index 00000000000..221e2f69815
>> --- /dev/null
>> +++ b/gcc/config/riscv/rtems.h
>> @@ -0,0 +1,31 @@
>> +/* Definitions for RISC-V RTEMS systems with ELF format.
>> +   Copyright (C) 2017 Free Software Foundation, Inc.
>> +
>> +   This file is part of GCC.
>> +
>> +   GCC is free software; you can redistribute it and/or modify it
>> +   under the terms of the GNU General Public License as published
>> +   by the Free Software Foundation; either version 3, or (at your
>> +   option) any later version.
>> +
>> +   GCC is distributed in the hope that it will be useful, but WITHOUT
>> +   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
>> +   or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
>> +   License for more details.
>> +
>> +   Under Section 7 of GPL version 3, you are granted additional
>> +   permissions described in the GCC Runtime Library Exception, version
>> +   3.1, as published by the Free Software Foundation.
>> +
>> +   You should have received a copy of the GNU General Public License and
>> +   a copy of the GCC Runtime Library Exception along with this program;
>> +   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
>> +   <http://www.gnu.org/licenses/>.  */
>> +
>> +#undef TARGET_OS_CPP_BUILTINS
>> +#define TARGET_OS_CPP_BUILTINS()               \
>> +    do {                                       \
>> +       builtin_define ("__rtems__");           \
>> +       builtin_define ("__USE_INIT_FINI__");   \
>> +       builtin_assert ("system=rtems");        \
>> +    } while (0)
>> --
>> 2.12.3
>>